Mechanical and electrical machinery can include a number of subsystems or components, such as a shaft, bearings, gears, impellers, stators, rotors, and so forth. The machinery and its subsystems are often monitored to detect potential failures (such as faults) at an early stage in order to prevent secondary damage, save maintenance costs, improve plant uptimes (such as machine availability), save potential financial losses from plant downtime, and assist towards increasing productivity. The monitoring can include a variety of signal processing, pattern recognition, or statistical techniques.
Monitoring systems (such as health monitors) often utilize various signal processing techniques, such as Fast Fourier Transform (FFT) analysis, enveloping, time-frequency analysis and wavelet transforms, to detect defects in individual subsystems. However, since subsystems interact with each other, monitoring any subsystem in isolation can create a number of false positives or true negatives. In addition, a conflict can exist between two or more subsystems that the monitoring system may be unable to solve.